U.S. patent application number 10/489504 was filed with the patent office on 2005-02-24 for apparatus and method for treatment of long bone fractures.
Invention is credited to Challis, Murray John, Hickey, Terence John.
Application Number | 20050043659 10/489504 |
Document ID | / |
Family ID | 3831579 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050043659 |
Kind Code |
A1 |
Challis, Murray John ; et
al. |
February 24, 2005 |
Apparatus and method for treatment of long bone fractures
Abstract
An apparatus and method for treating a long bone fracture in the
limb of an animal wherein a non-invasive technique is provided for
intermittently inducing a shortening in length of the skeletal
musculature surrounding the long bone, whereby a compressive force
may be intermittently applied to the fractured bone. Suitably a
radial inward force is applied substantially fully around the
circumference to the limb, by an inflatable cuff or sleeve, that is
transmitted to the surrounding muscles. Alternatively, electrical
signals cause active contraction of the musculature. The treatment
may include the application of about 55 to 65 compressions each day
for at least 10 days, and commencing within about 7 days of the
fracture being sustained. The compressions, applied with frequency
in the range of 0.05 Hz to 2 Hz, are desirably just short of that
which produces fracture site pain and the intensity of the
compressions may be increased between treatment sessions,
consistent with heating.
Inventors: |
Challis, Murray John;
(Verrierdale, AU) ; Hickey, Terence John; (Mount
Elisa, AU) |
Correspondence
Address: |
OHLANDT, GREELEY, RUGGIERO & PERLE, LLP
ONE LANDMARK SQUARE, 10TH FLOOR
STAMFORD
CT
06901
US
|
Family ID: |
3831579 |
Appl. No.: |
10/489504 |
Filed: |
October 1, 2004 |
PCT Filed: |
September 18, 2002 |
PCT NO: |
PCT/AU02/01279 |
Current U.S.
Class: |
602/5 |
Current CPC
Class: |
A61N 1/36003 20130101;
A61F 5/012 20130101; A61F 5/05816 20130101 |
Class at
Publication: |
602/005 |
International
Class: |
A61F 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2001 |
AU |
PR 7739 |
Claims
1. A method for treating a long bone fracture in a limb of an
animal or a human, the method comprising the steps of:
non-invasively and intermittently inducing a shortening in the
axial length of skeletal musculature surrounding the fractured long
bone in said limb; whereby the skeletal musculature intermittently
applies a longitudinal compressive force to the fractured bone.
2. The method of claim 1 wherein the step of inducing the
shortening in the axial length of skeletal musculature is achieved
by applying a force or stimulus radially to the outside of the limb
that is transmitted to the surrounding muscles.
3. The method of claim 2 wherein the radial force or stimulus is
applied dynamically in that it varies as a function of time.
4. The method of claim 2 wherein the radial force or stimulus is
applied at regular intervals.
5. The method of claim 2 wherein the radial force or stimulus is
applied to the outside of the limb in a balanced fashion.
6. The method of claim 2 wherein the radial force or stimulus is
applied substantially fully around the circumference of the
limb.
7. The method of claim 2 wherein the radial force or stimulus is
applied by a transmitting member that extends around the outside of
the limb.
8. The method of claim 7 wherein the transmitting member is
displaced along the limb so as to be longitudinally spaced from the
fracture.
9. The method of claim 2 wherein the radial force or stimulus has a
magnitude below that which causes the patient fracture site
pain.
10. The method of claim 9 wherein the radial force or stimulus has
a magnitude just below that which causes fracture site pain or at
most moderate discomfort.
11. The method of claim 7 wherein the transmitting member is a
mechanical force application member which applies pressure to the
outer surface of the limb.
12. The method of claim 7 wherein the transmitting member is an
electrical signal transmitter which applies electrical stimulus to
the outer surface of the limb.
13. The method of claim 11 wherein the duration of application of
the force or stimulus is between about 2 to 7 seconds.
14. A method for treating a long bone fracture in a limb of an
animal or a human, the method comprising the steps of:
non-invasively and intermittently inducing a shortening in the
axial length of skeletal musculature surrounding the fractured long
bone in said limb by applying a force or stimulus radially to the
outside of the limb that is transmitted to the surrounding muscles;
whereby the skeletal musculature intermittently applies a
longitudinal compressive force to the fractured bone to effect a
plurality of compressions of the fractured bone over a
predetermined period of time in a treatment session.
15. The method of claim 14 wherein the treatment session includes
applying at least 20 compressions to the fracture.
16. The method of claim 14 wherein the treatment session comprises
from about 40 to 70 compressions.
17. The method of claim 14 including at least one treatment session
each day.
18. The method of claim 17 including two treatment sessions each
day spaced 8 to 16 hours apart.
19. The method of either claim 17 or claim 18 wherein the treatment
sessions are conducted for at least 10 days.
20. The method of claim 17 wherein the treatment sessions commence
within about 5 to 10 days post fracture.
21. An apparatus for treating a long bone fracture in the limb of
an animal or human, said apparatus comprising: non-invasive means
for intermittently inducing a shortening in the axial length of the
skeletal musculature surrounding the long bone, whereby a
compressive force may be intermittently applied to the fractured
bone.
22. The apparatus of claim 21 wherein the means for inducing a
shortening of the skeletal musculature comprises a force
application member for applying a force radially to the limb that
is transmitted to the surrounding muscles.
23. The apparatus of claim 22 wherein the force application member
is adapted to apply the radial force dynamically, in that the force
may be varied as a function of time.
24. The apparatus of claim 22 wherein the radial force may be
selectively applied at regular intervals in the range from 0.05 Hz
to 2 Hz.
25. The apparatus of claim 22 wherein the radial force is applied
to the outside of the limb in a balanced fashion.
26. The apparatus of claim 22 wherein the radial force is applied
to the limb by a force application member extending fully
circumferentially around the limb.
27. The apparatus of claim 22 wherein the force application member
is adapted to apply the radial force for a short period and then
released the limb, and thereafter this cycle of force application
and release may be repeated.
28. The apparatus of claim 22 wherein the force application member
is a sleeve or cuff that passes over the limb of a patient, which
sleeve or cuff is expandable and contractible on demand to apply
said force to the limb of the patient.
29. The apparatus of claim 28 wherein the sleeve or cuff has a
generally ring or toroidal shaped body that is adapted to retain a
fluid in said body.
30. The apparatus of claim 28 wherein the force application member
may be inflated and deflated on demand by the forced introduction
and subsequent release of air through a valve and/or fluid a
coupling.
31. The apparatus of claim 21 further comprising an immobilisation
member for immobilising the fractured limb of the patient.
32. The apparatus of claim 31 wherein the immobilisation member
comprises a relatively rigid cast of plastic or plaster for
supporting the limb.
33. The apparatus of claim 31 wherein the force application member
is positioned under the immobilisation member, preferably
sandwiched between the immobilisation member and the skin of the
patient.
34. The apparatus of claim 31 wherein the force application member
is positioned adjacent the immobilisation member, preferably
abutting the proximal end of said immobilisation member.
35. The apparatus of claim 31 wherein the valve or fluid coupling
projects through the immobilisation member and provides one form of
attachment of the cuff to the cast.
36. The apparatus of claim 31 may further including a means for
selectively inflating the cuff with compressed air to a
predetermined pressure for a predetermined time and then deflating
the cuff by releasing said pressure.
37. The apparatus of claim 21 adapted for delivering the treatment
of a method for treating a long bone fracture in a limb of an
animal or a human, the method comprising the steps of:
non-invasively and intermittently inducing a shortening in the
axial length of skeletal musculature surrounding the fractured long
bone in said limb: whereby the skeletal musculature intermittently
applies a longitudinal compressive force to the fractured bone.
38. The apparatus of claim 21 wherein the means for inducing a
shortening of the skeletal musculature comprises an electrical
signal transmitter for generating an electrical impulse for
stimulating the skeletal musculature and thereby causing it to
contract and shorten to apply longitudinal compression to the
bone.
39. The apparatus of claim 38 wherein the electrical signal
transmitter comprises a signal transmitting member that is placed
in contact with the outer surface of the limb of the patient that
applies an electrical stimulus to the limb of the patient.
40. The apparatus of claim 38 further comprising electrodes placed
on the skin of a user, which electrodes are arranged to pass fully
circumferentially around the arm of a user for application of said
stimulus so as to induce contraction of the muscles in the limb
traversing the fracture.
41. The apparatus of claim 38 wherein the signal generator is of
the battery powered portable type.
42. The apparatus of claim 38 wherein the signal generator is
programmable.
43. The apparatus of claim 38 wherein the signal generator is
associated with a data recorder for recording details of the
electrical stimulus applied to the musculature.
44. The apparatus of claim 38 wherein the electrical stimulus
comprises an underlying carrier signal that is amplitude modulated
by an impulse signal.
45. The apparatus of claim 44 wherein the carrier signal has a
frequency in the range from about 30 Hz to 50 Hz.
46. The apparatus of either claim 44 or claim 45 wherein the
impulse signal has a frequency in the range from 0.05 to 2 Hz.
47. A compression apparatus for inflating and deflating a cuff or
sleeve of an apparatus for treating a long bone fracture in the
limb of an animal, the apparatus adapted for selectively
pressurising and inflating the cuff by supplying compressed air to
the cuff and subsequently deflating the cuff, such that the cuff
may be intermittently inflated and deflated; said compression
apparatus comprising: inflation device for inflating the cuff or
sleeve such that the cuff applies pressure radially inwardly to the
limb and, after a desired compression of the fracture has been
achieved; pressure relief device for relieving that pressure from
the limb by deflating the cuff; and timer for controlling
respective durations of inflation and deflation.
48. The compression apparatus of claim 7 further comprises: a
closed tank container for supplying pressurized fluid; a valve
having an air inlet port operatively coupled to the pressurised
fluid supply and a vent port for venting fluid to the atmosphere in
parallel with the inlet port; a cuff coupling for operatively
coupling the valve to the cuff; the valve having a switch for
switching either the fluid inlet port or the vent port to the cuff
at any one time, whereby only one of the fluid inlet or the vent
port can be coupled to the cuff or sleeve, whereby the apparatus is
either in compression mode or in deflation mode at any one
time.
49. The compression apparatus of claim 48 wherein the valve
comprises a solenoid actuated two-way valve and the pressurised
fluid is compressed air.
50. The compression apparatus of claim 47 wherein the timer means
further includes timer setting device for setting the duration for
which the cuff is inflated and also the duration for which the cuff
is deflated. 51. The method of claim 12, wherein the duration of
application of the force or stimulus is between about 2 to 7
seconds.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a method of treating a long bone
fracture in a warm-blooded animal, particularly a human being, in
order to promote the healing of the fracture. The invention also
extends to an apparatus for use in promoting the healing of long
bone fractures and a compression device for use with the
apparatus.
[0003] This invention relates particularly, but not exclusively, to
a method and apparatus for treating fractures of the distal radius,
i.e. of the forearm. It will therefore be convenient to hereinafter
describe the invention with reference to this example application.
It is to be clearly understood however that the invention is
capable of broader application, for example it might be applied to
leg bones and also other long bones.
[0004] 2. Discussion of the Background Art
[0005] Long bone fractures are fairly common injuries for animals,
including human beings. They typically result from externally
applied trauma as a result of accidents, such as falls, motor
vehicle accidents, sporting injuries or the like. Typical long bone
fractures include tibia and fibula fractures of the lower leg,
femur fractures of the upper leg and humerus, ulna and radius
fractures of the arm.
[0006] The established clinical treatment of these fractures
involves immobilising the fractured limb, e.g. by means of a
plastic or a plaster cast, until such time as the bone has knitted
at the fracture site. Thereafter the patient is treated with
physiotherapy to restore limb function, strength and range of
movement. The latter is particularly important as immobilisation
results in some muscle atrophy and joint stiffness and muscle tone
needs to be restored. Where some displacement of the fractured bone
has occurred it is also necessary to position the opposed ends of
the fractured bone in face to face abutment before the limb is
immobilised.
[0007] The time taken for the healing of a fracture naturally
varies from case to case. A particularly important factor is the
mechanical environment of the fracture site. Fracture healing time
also depends on factors such as the severity of the fracture, the
age of the patient, and the bone physiology of the patient. It is
also known in patients with long bone fractures, particularly those
sustained to the leg bones, that the reintroduction of normal
mechanical stimulus to the fracture, such as by weight bearing
during assisted walking, can improve bone healing: see Goodship, A.
E. & Kenwright, J.; "The influence of induced micromovement
upon the healing of experimental tibial fractures", J. Bone and
Joint Surg., 67-B(4):650-655, 1985.
[0008] Naturally the time taken for a patient to restore function
and range of movement can be very important to a patient in the
modern world. Many people rely on the use of their arms and hands
to earn a living, for example sportspeople, manual labourers, brick
layers or typists to name a few. These people would generally want
a fracture to heal as quickly as possible. Clearly therefore any
development that was able to accelerate the repair and healing of
long bone fractures, particularly common fractures such as
fractures of the distal radius, would be commercially very
important.
[0009] It is known in the art to use an external fixation device to
hold fractured bone/s in position during a healing process. This
treatment tends to be used on more complex fractures. An external
fixation device generally comprises broadly attachment elements
directly attached to the bone on either side of the fracture and
projecting laterally outwardly through the skin of a patient. The
attachment elements are then attached to each other by at least
one, typically two, longitudinal tensioning elements. The
longitudinal elements apply a longitudinal compressive force to the
fractured bones to hold the bones together for correct knitting of
the fracture. An external fixation device is invasive passing
through the skin and flesh of the patient and being directly
attached to the bone of a user.
[0010] It has been known to vary the compressive force applied to
the bone having the fracture using the external fixation device.
This typically involves manual adjustment of the longitudinal
tensioning element. It is also known that the dynamic loading of
long bone fractures using an external fixation device can increase
the rate of healing of a long bone fracture, such as described for
example in U.S. Pat. No. 5,997,490 (McLeod et al) which involves a
cyclical stimulation having a frequency of between about 5 Hz and
about 20 kHz. This specification also happens to contain a useful
review of the related prior art. However it is not really practical
to apply an external fixation device to a fracture site simply to
get some speeding up of the healing process. The treatment is
simply too complex and too invasive.
[0011] However, it would clearly be advantageous if a non-invasive
apparatus and method could be devised for taking advantage of this
discovery, namely that dynamic loading of the fracture site tends
to speed up the healing of long bone fractures. Such a method and
apparatus would enable this discovery to be conveniently and widely
used to accelerate healing of long bone fractures and thereby
improve quality of life for patients.
SUMMARY OF THE INVENTION
[0012] Object of the Invention
[0013] It is therefore an object of the present invention to
provide a practical, non-invasive apparatus and corresponding
method for the dynamic loading of long bone fractures to enhance or
accelerate healing of many commonplace long bone fractures, such as
fractures of the distal radius.
[0014] Other objects of the present invention will be apparent from
consideration of the following description.
[0015] Disclosure of the Invention
[0016] According to an aspect of this invention there is provided a
method for treating a long bone fracture in a limb of an animal or
a human, the method including the steps of:
[0017] non-invasively and intermittently inducing a shortening in
the axial length of skeletal musculature surrounding the fractured
long bone in said limb;
[0018] whereby, the musculature intermittently applies a
longitudinal compressive force to the fractured bone.
[0019] The step of inducing of shortening in the length of the
musculature can be achieved non-invasively by either causing the
muscles to contract by a stimulus, such as an electrical stimulus
or else by applying a radial force to the outside of the limb that
is transmitted to the muscles to cause a shortening in the
longitudinal length thereof.
[0020] The force or stimulus may be dynamic in the sense that it
varies as a function of time. Preferably the force is applied at
regular intervals and in a balanced fashion.
[0021] In one form the force may be applied by a force transmitting
member that extends fully circumferentially around the limb, and
the force may be applied substantially fully radially inwardly
around the circumference of the limb.
[0022] The forces may be applied to the fractured limb to effect a
plurality of compressions of the long bone over a predetermined
period of time, for example in a treatment session.
[0023] The method may include applying at least 20 compressions in
a treatment session, preferably 40 to 70 compressions, more
preferably about 55 to 65 compressions in a session.
[0024] The compressions suitably involve application of a force
having a magnitude below that which causes the patient pain at the
fracture site, suitably a magnitude just below that which causes
pain or at most moderate discomfort. Further the compressions may
all be of substantially the same magnitude so as to apply the same
force to the surface of the limb of the patient each time it is
applied. Further each compression may last 2-7 seconds, preferably
3-4 seconds.
[0025] In another form of the present invention, the shortening in
the length of skeletal musculature surrounding the fractured long
bone is induced by an electrical stimulus provided by an electrical
signal transmitter. The muscles may be stimulated with the same
frequency and intensity as described above with reference to the
compressions.
[0026] Suitably as healing takes place, the electrical stimulus or
mechanical forces might be increased in amplitude every few days or
every week up to the point that falls just short of producing
fracture site pain or at most moderate discomfort. The method may
include at least one treatment session as described above each day,
preferably two treatment sessions each day spaced 8 to 16 hours
apart, e.g. 10 to 14 hours apart. Preferably the method includes
conducting the treatment sessions for at least 10 days, preferably
at least 20 days and more preferably for at least 28 days,
depending on the particular fracture. Typically the treatment
sessions might commence about 7 days post fracture, and preferably
within 5 to 10 days.
[0027] According to another aspect of this invention there is
provided an apparatus for treating a long bone fracture in the limb
of an animal or human, said apparatus including:
[0028] non-invasive means for inducing a shortening in the axial
length of the skeletal musculature surrounding the long bone,
whereby a compressive force may be intermittently applied to the
fractured bone.
[0029] In one form of the apparatus, known as the fracture cuff
form, the means for inducing a shortening of the skeletal
musculature may comprise a force application member applying a
force to the limb of the patient. This external application of
force causes a shortening in the longitudinal length of the
musculature.
[0030] Typically the force is applied to the surface of the skin of
the patient, i.e. in a radial inward direction, and the force
application member extends fully around the limb of the patient,
and suitably applies a force fully circumferentially around the
limb of the patient.
[0031] The force application member need not apply the force fully
around the circumference of the limb of a user. It is however
highly desirable that the force is balanced, for example by
diametrically opposed radially inwardly directed forces that
balance with one another. Thus the apparatus applies pressure
externally to the fractured limb of a patient, i.e. non-invasively,
to cause a shortening in the longitudinal length of the skeletal
musculature which in turn applies compression to the fractured
bone.
[0032] Further the force application member most suitably applies
the force dynamically, for example intermittently with a frequency
in the range of 0.05 Hz to 2 Hz, preferably from about 0.1 Hz to 1
Hz. That is, the pressure is applied for a short period and then
released by the force application member, and thereafter this cycle
of force application and release may be repeated.
[0033] The force application member may be a sleeve or cuff or
bladder that passes over the limb of a user and that is expandable
and contractible on demand to apply said force to the limb of the
patient. Any material or means may be used to expand and contract
the cuff and it need not be a fluid. Conveniently the sleeve or
cuff is inflated with a gas, for example air.
[0034] An inflatable sleeve or cuff typically having a length of
10-25 cm may be formed by joining two superimposed sheets joined
together around the edges. It typically has a flattened shape when
in a deflated condition. Typically the sleeve or cuff is desirably
formed in a ring or toroidal shape, being continuous in the sense
that it does not have means for opening the sleeve at a point. It
may be fitted to a patient by passing it through the hand of the
patient and over the arm.
[0035] In a particularly preferred form, the force application
member may be inflated and deflated on demand by the forced
introduction and subsequent release of air, for example through a
valve. While it is practical and convenient to use air, it is to be
appreciated that any other form of fluid may also be used.
[0036] Thus compressed air may be used to inflate the sleeve or
cuff and apply a force in the form of cuff pressure to the limb,
for example the arm of a patient. Thereafter the air may be vented
to deflate the sleeve and relieve the pressure.
[0037] Typically the apparatus also includes an immobilisation
means for immobilising the fractured limb of the patient. In one
form the immobilisation means comprises a rigid cast of plastic or
plaster.
[0038] The force application member, for example the cuff, may be
positioned under the immobilisation member, i.e. sandwiched between
the immobilisation member and the skin of the patient.
Alternatively, the force application member may be adjacent the
immobilisation member, preferably abutting the proximal end of the
immobilisation member. Conveniently the force application member
may be attached to the immobilisation member, although this is not
necessary.
[0039] When the force application member is an inflatable cuff, it
may incorporate a valve for selectively inflating and deflating the
cuff and the valve may project through the immobilisation member to
the outside where it can easily be coupled to an inflation device,
for example a pump. Alternatively, the valve may be remote from the
cuff which includes a coupling projecting through the
immobilisation member. This may provide one form of attachment of
the cuff to the plaster cast in one form.
[0040] The apparatus may further include a means for selectively
inflating the cuff with compressed air to a predetermined pressure
for a predetermined time and then deflating the cuff. Furthermore,
the inflating means may be controlled by timing means.
[0041] In another form of the apparatus, called the electrical
impulse form, the means for inducing a shortening in the axial
length of the skeletal musculature comprises an electrical signal
transmitter for generating an electrical impulse for stimulating
the skeletal musculature and thereby causing it to contract and
shorten to apply longitudinal compression to the bone.
[0042] The electrical signal transmitter may comprise a signal
transmitting member that is placed in contact with the outer
surface of the limb of the patient and applies an electrical
impulse to the limb of the patient. Typically the member might be
an electrode placed on the skin of a user. The electrode may be
arranged to pass fully circumferentially around the arm of a user
so as to induce contraction of muscles in the limb at the same
time. This arrangement helps to achieve simultaneous coordinated
contraction of the musculature, including those muscles traversing
the fracture.
[0043] The electrical signal transmitting member may deliver an
electrical impulse that resembles that delivered by a
transcutaneous electrical nerve stimulation (TENS) apparatus used
in physiotherapy, or more particularly that delivered by a high
voltage pulsed current therapeutic device similar to that used for
rehabilitation of weak muscles. The TENS apparatus has a small
silver plated electrode that is placed on the skin of the
patient.
[0044] The electrical impulses cause contraction of the skeletal
musculature of the fractured limb which applies a longitudinal
compression to the bone. The electrical impulses are applied
intermittently as described above for the fracture cuff form of the
invention. The signal transmitting member, for example electrode,
may be electrically coupled to a signal generating means of a type
that is well known in the art. Such a generator would typically be
portable, be battery powered and suitability utilise digital logic
circuits to allow desired stimulus to be programmed as
required.
[0045] The electrical stimulus comprises an underlying carrier
signal that is amplitude modulated by an impulse signal. The
carrier signal preferably has a frequency in the range from about
30 Hz to 50 Hz, whilst the modulating impulse signal has a
frequency in the range of 0.05 Hz to 2 Hz, most suitably from about
0.1 Hz to 1 Hz.
[0046] According to a third aspect of this invention there is
provided a compression apparatus for inflating and deflating the
cuff or sleeve (in the fracture cuff form of the apparatus), the
apparatus pressurising and inflating the cuff by supplying
compressed air to the cuff and then also deflating the cuff after
it has been inflated, such that the cuff is intermittently inflated
and deflated, for example on a regular basis.
[0047] Thus the compression apparatus comprises means for inflating
a cuff such that it applies pressure radially inwardly to the limb,
for example arm, of the user and then, after the desired
compression of the fracture has been achieved, relieves that
pressure and deflates the cuff and then thereafter compresses the
sleeve again, etc.
[0048] The compression means may comprise a closed tank container,
a valve means having an air inlet port operatively coupled to the
pressurised air supply and a vent port for venting air to the
atmosphere in parallel with the compressed air inlet, and a cuff
coupling for operatively coupling the valve means to the cuff, the
valve means having a switch means for switching either the
compressed air inlet port or the vent port to the cuff at any one
time.
[0049] Thus only one of the compressed air inlet or the vent for
compressed air can be coupled to the bladder or cuff at any one
time. Thus the apparatus is either in compression mode or deflation
mode at any one time. Conveniently the valve means may comprise a
solenoid actuated valve, for example a 240 volt solenoid valve.
[0050] The pressurised air supply may comprise a pressurised tank,
for example a cylinder of air.
[0051] The apparatus may also include a compressor in communication
with the closed tank, and means for isolating the compressor from
the tank once sufficient compressed air has been pumped into the
tank. Thus the compression apparatus permits the amount of air that
is pumped into the tank to be varied before it is isolated.
[0052] Once the tank has been isolated from the compressor, the
valve means opens placing the tank in communication with the cuff
and allowing the cuff to be filled with compressed air. The
pressure generated in the cuff depends on the amount of compressed
air admitted to the cuff from the storage tank, which can be
regulated as desired.
[0053] The compressor apparatus may further include timer setting
means for setting the time for which the cuff is inflated
(inflation time) and also the time for which the cuff is deflated
(deflation time). Typically the switch means associated with the
valve means switches between the compressed air inlet port and the
vent port based purely on time, for example a predetermined time
interval.
[0054] Typically the apparatus also includes typical safety
features such as a pressure cut-out switch to prevent
over-pressurising the storage tank.
BRIEF DETAILS OF THE DRAWINGS
[0055] An apparatus and a method in accordance with this invention
may manifest itself in a variety of forms or embodiments. It will
be convenient to hereinafter describe in detail one preferred
embodiment of the invention with reference to the accompanying
drawings. It is to be clearly understood however that the detailed
nature of this specific description does not supersede the
generality of the preceding broad description outlining the general
principles of the invention. In the accompanying drawings:
[0056] FIG. 1 is a schematic sectional side view of apparatus in
accordance with one embodiment of the invention, namely a fracture
cuff, mounted on a patient's arm for treating a fracture of the
distal radius or wrist;
[0057] FIG. 2 is a side view of the fracture cuff of FIG. 1,
showing the application of pressure to the arm of the patient;
[0058] FIG. 3 is a schematic circuit diagram of a compression
apparatus used with the apparatus of FIG. 1;
[0059] FIG. 4 is a graph showing pressure as a function of time
during the typical treatment session;
[0060] FIG. 5A is a graph plotting recovery in grip strength as a
function of time after a fracture using the invention compared with
standard treatment;
[0061] FIG. 5B is a graph plotting recovery in pinch strength as a
function of time after a fracture using the invention compared with
standard treatment;
[0062] FIG. 5C is a graph plotting recovery in key grip strength as
a function of time after a fracture using the invention compared
with standard treatment;
[0063] FIG. 5D is a graph plotting recovery in isometric supination
strength as a function of time after a fracture using the invention
compared with standard treatment;
[0064] FIG. 6 is a schematic sectional side view of an apparatus in
accordance with another embodiment of the invention, which employs
electrical impulses;
[0065] FIG. 7 is a graph depicting the electrical stimulation
signal as a function of time during the typical treatment session;
and
[0066] FIG. 8 is a graph showing the compression force at a
fracture site resulting from use of the embodiment of the invention
described in relation to FIGS. 1 to 4 above.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0067] In FIGS. 1 and 2, reference numeral 10 refers generally to
an apparatus in accordance with a first embodiment of the
invention. The apparatus 10 includes an immobilisation cast 12 for
a fracture 14 of the distal radius 11 of a patient. The cast 12 is
fitted around the fractured arm 13 of the patient and a force
application member 15 is sandwiched between the immobilisation cast
12 and the outer surface or skin of arm 13.
[0068] The immobilisation cast 12 may be in the form of a moulded
plastic cast or else in the form of a well known plaster cast that
is shaped to fit the arm of the patient. The structure and function
of the immobilisation cast 12 would be well known to persons
skilled in the art and will not be described in further detail in
this specification.
[0069] The force application member 15 in the illustrated
embodiment comprises an inflatable cuff or sleeve or bladder that
extends circumferentially around the arm of the patient. The cuff
15 is similar to an inflatable armband used to assist flotation of
infants in swimming pools. It is also similar to the cuffs used to
constrict the arm in blood pressure measurement devices, such as a
sphygmanometer, although the cuff of the embodiment has a ring or
toroidal type configuration.
[0070] The inflatable cuff 15 has a coupling 19 protruding through
the immobilisation cast 12 for passing compressed air into the cuff
15 and also for venting compressed air from the cuff 15, as
required. The coupling 19 is provided for coupling the cuff 15 via
a tube 18 to a valve of a compression apparatus, which will be
described in more detail below.
[0071] FIG. 3 is a schematic circuit diagram for a compression
apparatus 20 to be used with the cuff 15 shown in FIGS. 1 and 2.
Broadly, the apparatus 20 comprises a fluid circuit having an
electric motor (m) driven air compressor or air pump 22 in fluid
communication with an air tank 24 in the form of a stainless steel
cylinder. The compressor is electrically powered from a 240v AC
supply 25 through a main switch 21. The compressor 22 can be
isolated from the tank 24 once a predetermined quantity of
compressed air has been pumped into the tank, as will be described
in more detail below.
[0072] The air tank 24, in turn, is in fluid communication with a
valve in the form of a solenoid valve 26. The solenoid valve 26 has
two ports on one side, namely an air inlet port 28 and a vent port
30. The air inlet port 28 is coupled to the air tank 24 and the
vent port 30 is in fluid communication with an air vent to
atmosphere. The valve 26 has a third port 32 on the other side that
is in fluid communication with the cuff 15 via the tube 18 attached
to the coupling 19. The valve 26, which is electrically controlled
by solenoid winding 23, has the ability to switch between placing
the air tank 24 in communication with the cuff 15 through air inlet
port 28 and placing vent port 30 in communication with the cuff
15.
[0073] The compression apparatus 20 also includes an electrical
circuit having an inflation timer (T1) 34 for setting the time for
which the air tank 24 is coupled to the cuff. The apparatus further
includes a deflation timer (T2) 36 for determining the time for
which the vent port 30 is coupled to the cuff 15. Each of these
timers 34, 36 is continuously variable and can be individually set
by a user who thus has control over the times, and thereby also the
inflation and deflation cycle of the cuff 15.
[0074] The circuit diagram in FIG. 3 shows the inflation and
deflation timers (T1, T2) and respective indicators, including an
inflate indicator 33 in the form of a green LED (G), a deflate
indicator 35 in the form of a blue LED (B) and a high pressure
indicator in the form of a red LED (R) 37. The circuit for the
compression apparatus 20 also includes a start-up timer (T4) 38 and
a transition timer (T3) 39. The apparatus further includes a
high-pressure lockout relay (R3) 40 actuated by a pressure switch
(P) 41 coupled to the air tank 24 for shutting down the apparatus
20 if a predetermined air pressure is exceeded. This is a safety
feature. The structure and function of these features would be well
known to a person skilled in the art and accordingly will not be
described in further detail in the specification.
[0075] In use, the apparatus 20 is started up with the on/off
switch 21 and the compressor 22 starts to produce compressed air.
The inflation or compression stage is initiated by pumping a
certain volume of air into the tank 24 with the compressor 22. The
amount of air pumped into the tank 24 and thereby the air pressure
in the tank can be set as desired by a user. The tank 24 is then
isolated from the compressor and the valve 26 switched to allow the
air in the tank 24 to flow into the cuff 15 and inflate the cuff.
After the inflation time has elapsed, the valve 26 switches to put
the cuff or bladder 15 in communication with the vent port 30. This
permits air to vent from the cuff 15 to atmosphere. Again the
deflation time can be similarly set by a user by way of timer 36.
These time settings also enable the total duration and thereby the
frequency of the cycles to be adjusted. For example in one
application, the inflation stage may be set at 3.5 seconds and the
deflation stage at 6.5 seconds to give a total cycle time of 10
seconds and 6 cycles per minute.
[0076] In use the apparatus 10 as a whole is used to treat a
fractured limb, a fracture 14 of the distal radius 11 in the
example, in a number of treatment sessions to assist, enhance
and/or accelerate healing of the limb. The cuff 15 and specifically
the coupling 19 thereof is first coupled to the compression
apparatus 20 that supplies the compressed air via solenoid valve
26, and then the apparatus 20 is switched on. This causes the cuff
15 to inflate for a period of a few seconds, e.g. about 3.5 seconds
to a pressure where it stops short of inflicting any fracture pain
or at most moderate discomfort and then deflates releasing the grip
on the patient's arm 13. This grip and release of the arm 13 by the
cuff 15 in the present embodiment causes and/or simulates
co-contraction of the forearm skeletal musculature (not shown) and
applies a longitudinal compression force to the fracture 14.
[0077] This sequence of application of pressure to a
circumferential portion of the forearm for about 3.5 seconds and
then relieving the pressure for about 6.5 seconds constitutes the
compression cycle. The compression apparatus 20 then automatically
repeats this cycle over about 10 minutes, effecting about 60
compressions. Thereafter the compressed air is vented from the cuff
15 and the pressure is relieved from the forearm entirely.
[0078] The cuff or sleeve 15 is desirably inflated with compressed
air to the point where it applies a firm pressure, just short of
inflicting fracture site pain, radially inwardly against the flesh
of the arm of the patient, and maintains this pressure for about
3.5 seconds. The duration of each compression is substantially the
same. Further the intensity or strength of the force applied by the
cuff against the arm of a user is substantially the same for each
compression, as illustrated by the curve shown in FIG. 4. The
carrying out of the treatment to a patient generally does not cause
any pain or at most moderate discomfort.
[0079] The treatment sessions are suitably carried out twice a day
over about 4 to 6 weeks for fractures of the distal radius. The
treatment sessions may be carried out by the patients in their own
home without the assistance of a treatment specialist. The
applicant has conducted experiments on patients with fractures of
the distal radius to determine the effectiveness of the apparatus
of the preferred embodiment.
[0080] During these experiments, several patients had the fracture
cuff fitted within 5 to 14 days of the fracture being sustained,
with the average time being 9.4 days post fracture. The fracture
cuff comprised a normal plaster cast 12 fitted over the patient's
forearm with an inflatable cuff or sleeve 15 sandwiched between the
cast and the arm 13 in the region of the fracture 14. For a
fracture to the distal radius, the inflatable cuff or sleeve 15 is
suitably fitted to the proximal third of the forearm musculature or
approximately one third (1/3) of the way along the limb from the
patient's elbow. The patients were then subject to two treatment
sessions of about 10 minutes each per day with a fracture cuff over
a period of about four (4) weeks.
[0081] Each treatment session comprised coupling the cuff up to a
compression apparatus for inflating and deflating the cuff and then
intermittently pressurising and deflating the cuff to simulate
co-contraction of the forearm musculature of the patient. Each
compression of the cuff lasted for about 3.5 seconds and each
deflation lasted for about 6.5 seconds, giving a pressure
application frequency of about 0.1 Hz. Each patient received
exactly the same dosage of treatment for the treatment period.
[0082] A force applied to the forearm that was generally found not
to cause any fracture site pain, while still causing a fairly firm
compression of the forearm musculature, is most desirable. This
would typically be in the range of about 50 mmHg (6.67 kPa) to 300
mmHg (40 kPa) for a fractured wrist in an adult male. Practitioners
will however appreciate that the magnitude or intensity of pressure
will vary with the nature of the fracture, the stage of healing and
of course the patient's pain threshold. The inventors believe that
a compression that stops short of producing any pain at the
fracture site will optimise the osteogenic effect, but not
adversely interfere with or retard the healing process. Thus the
magnitude of pressure applied is governed by the patient's
perception of pain at the fracture site.
[0083] The rate of healing of each patient's fracture was assessed
or measured on a weekly basis. This rate of healing was compared
against the rate of healing for a control group of patients who did
not receive the treatment set out in this application. The
assessment of rate of healing was made by measuring limb function
as an indicator of biomechanical strength of the fracture site. The
level of function of the fractured arm and associated hand was
measured as a percentage of that of the non-fractured arm and
associated hand.
[0084] Grip strength was measured using a Jamar dynamometer
equipment in four (4) positions suited to the forearm. These four
measurement positions are as set out below:
[0085] grip strength in a sitting position with the elbow fully
extended;
[0086] pinch strength;
[0087] key grip strength; and
[0088] isometric supination strength.
[0089] The results of the inventor's experiment for patient
strength in each of the above positions are shown in FIGS. 5A to
5D. On average, a patient who was subjected to the treatment of the
present invention achieved, in only four (4) weeks, the mean
strength after six (6) weeks of patients who were not treated with
the invention. The inventor's experimental work demonstrates
clearly that healing of fractures of the distal radius occurred at
a significantly faster rate when the apparatus and method of the
invention was used.
[0090] The inventor also conducted experiments to verify that the
compression cuff does increase the application of compressive force
on the distal radius. A first experiment involved placing a
pressure sensor within the radio-carpal joint of a cadaver and then
fitting the cuff to the cadaver arm and cyclically inflating and
de-deflating the cuff, as described above. The measurements
registered by the pressure sensor showed that there was an increase
in compressive force in the joint when the cuff was inflated and
applied circumferential pressure was applied to the forearm
musculature. A transverse fracture of the distal radius shares a
similar orientation to the radio-carpal joint. A further experiment
was conducted using animal bones, namely from sheep, and employing
the cuff of the first embodiment of the present invention. The
forces detected across the ends of a fractured distal radius of a
sheep undergoing the cyclic pressure treatment using the cuff are
depicted in the graph shown at FIG. 8. This demonstrates that the
inventor's earlier assumption that the cuff and compression
apparatus would also produce these forces in a fracture of the
distal radius, is essentially correct.
[0091] FIG. 6 illustrates another embodiment of the apparatus
called the electrical impulse form. The apparatus comprises broadly
a signal transmitting member 50 electrically coupled to a signal
generator 53.
[0092] The member 50 includes two bands 54, 55 that extend fully
around the arm 13 of a patient and apply electrical impulse signals
directly to the skin of the patient. The electrically active part
of the member 50, comprising positive and negative electrodes
carried or comprised by respective bands 54, 55, also extend fully
around the limb of the patient. The signal transmitting member 50
is received within an immobilisation cast 51 much like the
embodiment described above with reference to FIGS. 1 and 2. Each of
the bands has an electrical terminal 52 projecting out through an
opening in the cast 51 which in use couples the electrodes to the
signal generator 53.
[0093] In use for each treatment session the generator 53, which is
powered by a battery pack 56, is coupled to the signal transmitting
member 50. The generator 53 is then switched on to cause
intermittent electrical stimulus to be transmitted by means of the
bands 54, 56 through the skin to the musculature of the limb, in
particular the muscles traversing the fracture 14. The bands are
suitably fitted to the limb adjacent the motor end points of the
muscles, which are usually found in the proximal third of said
muscles. The application of the electrical stimulus causes, in
response, contraction of the musculature to which applies
longitudinal compression to the fractured bone similar to that
achieved with the fracture cuff 15, except that in this embodiment
the contraction of the musculature is active rather than
passive.
[0094] The duration of each treatment session and the frequency of
treatment sessions is broadly similar to those described above with
reference to FIGS. 1 and 2. However, it will be appreciated from
the preferred signal characteristic 70 depicted In FIG. 7, the
electrical stimulation signal of this embodiment employs a carrier
signal (not to scale in the drawing for reasons of clarity), having
a frequency in the range of about 30 Hz to 50 Hz, that is amplitude
modulated by the desired impulsive stimulus. The underlying carrier
frequency range of about 30 Hz to 50 Hz was chosen in view of the
known physiological responses of the local nervous system to high
voltage pulsed current.
[0095] The impulsive stimulus signal has a relatively fast rise 71,
with a short hold at maximum amplitude 72 (of about 0.5 s),
followed by a slower decay 73, resulting in a modulated signal
having a somewhat saw-tooth shaped outer envelope. The amplitude of
the signal may vary in the range from 0 to 500v, with appropriately
low current, consistent with safe electro-medical practice. It will
be appreciated that the signal generator 53 may be programmable
such that any desired characteristic may be selected by a
clinician, as required.
[0096] The signal generator 53 is suitably provided with
adjustments for each of the frequency (f) of the underlying carrier
signal, the maximum amplitude of the impulsive signal (V) and the
period (P) of the modulating stimulus. Typically the amplitude is
adjusted steadily upward from a nominal value, in order that
compressions may be applied to the fracture without causing pain or
at most moderate discomfort to the patient. As discussed earlier,
it will be appreciated that variations in the nature of the
fractures, the patients and stage of healing call for different
parameter settings.
[0097] The electrical impulse form of the invention has the
advantage that stimulation of the musculature to actively effect
periodic compression of the fracture site assists in the reduction
of muscle wastage, which accompanies immobilised limbs. Furthermore
the apparatus, when in the form of a portable battery operated
signal generator is compact and may be conveniently and discretely
used at any time by the patient, has few moving parts and is
susceptible to low cost production. A data recorder 57 may also be
included for recording the time, date, duration and other details
of the treatment. This can assist clinical monitoring of patients
that are undertaking self-treatment, in that the recorded data will
reveal whether the prescribed treatment regime is adhered to by a
patient.
[0098] In some circumstances, such as patients prone to epileptic
episodes or having metal implants or heat pacemakers, the air
pressure cuff will find application.
[0099] The essence of the present invention resides in the
discovery that active or passive contraction of the musculature
associated with the fractured limb causes longitudinal compression
of the fracture site and thereby aids in healing the fracture.
Further the contraction of the musculature may be induced
non-invasively by an external agency.
[0100] Without being bound by theory, the applicant believes that
mechanical stimulation of the fracture site described above
stimulates new bone formation at the fracture site. Desirably the
mechanical stimulation should be consistent with normal usage, for
example at or below normal walking pace. By contrast the current
standard clinical treatment for long bone fractures namely of a
rigid immobilisation of the fractured limb substantially decreases
if not removes mechanical stimulation of the joint site at a time
when the rate of new bone production is required to be at its
highest.
[0101] The applicant believes it likely that the frequency range,
duration and intensity of electrical stimulation or mechanical
compression all influence the rate of bone healing in a fracture
and therefore applicant envisages increasing the duration or
intensity of each electrical stimulation or mechanical compression
progressively as the bone heals. As the bone heals it should be
able to withstand greater stimuli without the patient suffering
fracture site pain or at most moderate discomfort. For example one
or more of the frequency, duration or intensity of treatment may be
graduated, for example increased, as the bone healing
progresses.
[0102] Treatment protocols will be developed directed to enhancing
and optimising the osteogenic effect without increasing discomfort
to the patient in the form of fracture site pain or causing damage
to the healing fracture site. For example the mechanical pressure
or electrical stimulus might be increased every few days or every
week up to the point that falls just short of producing fracture
site pain. It is expected that the point just short of pain will be
different for different patients and different fractures.
[0103] An advantage of the treatment described above with reference
to the drawings, is that the treatment has been found to enhance
the rate of healing of the fracture. The increase in rate of
recovery shown in FIGS. 5A to 5D is very significant, since bone
strength is increased at least 25% in comparison with conventional
treatment and therefore would shorten the typical recovery time by
at least a couple of weeks. A further advantage is that it is
non-invasive and does not expose the patient to risk of infection
or other injury. Further the treatment does not cause discomfort or
pain to the patient.
[0104] A yet further advantage is that, upon provision of the
necessary apparatus, treatment can be carried out by a patient in
their home. The treatment does not need to be administered by a
health care professional, since it is substantially automated. This
makes it more user-friendly and suited to the modern lifestyle
where many people have difficulty finding time to visit
clinics.
[0105] A still further advantage of the apparatus described above
with reference to the drawings is that it is relatively simple,
particularly in the cuff or sleeve embodiment. This helps to make
the technology affordable and also predictable and reliable in
operation. A yet further advantage of this simplicity is that it
should help in obtaining acceptance of the technology by health
care providers.
[0106] It will of course be realised that the above has been given
only by way of illustrative example of the invention and that all
such modifications and variations thereto as would be apparent to
persons skilled in the art are deemed to fall within the broad
scope and ambit of the invention as is herein set forth in the
following claims.
* * * * *